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[2021.1] GeoTol messes with my nominals, why?

Running 2021.1, first encounter with GeoTols. Opened a program created in 2019 (I think) and upon running the program, the reported nominals are not the same as the feature nominals - why?



Loaded CAD to verify nominals were correct, still no go. Recreating the FCF doesn't change anything either.

Program:


START =ALIGNMENT/START,RECALL:USE_PART_SETUP,LIST=YES
ALIGNMENT/END
MODE/MANUAL
CHECK/3,1
FORMAT/TEXT,OPTIONS,ID,HEADINGS,SYMBOLS, ;MEAS,NOM,TOL,DEV,OUTTOL, ,
LOADPROBE/3MM
TIP/TIP1, SHANKIJK=0, 0, 1, ANGLE=0
COMMENT/OPER,NO,FULL SCREEN=NO,AUTO-CONTINUE=NO,
Mät ytterdiameter på vänster rörände

OBS! Börja med tre stödpunkter!
Ø22 =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
THEO/<0,0,0>,<0,0,1>,22,0
ACTL/<627.234,644.389,262.38>,<0.2742149,0.1856828,0.94 3572>,21.968,0
TARG/<0,0,0>,<0,0,1>
START ANG=0,END ANG=360
ANGLE VEC=<1,0,0>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
PKT Ø22 =FEAT/POINT,CARTESIAN,NO
THEO/<0,0,0>,<0,0,1>
ACTL/<627.234,644.389,262.38>,<0.2742149,0.1856828,0.94 3572>
CONSTR/POINT,CAST,Ø22
DATDEF/B,FEATURES=Ø22,,
A1 =ALIGNMENT/START,RECALL:START,LIST=YES
ALIGNMENT/TRANS,XAXIS,PKT Ø22
ALIGNMENT/TRANS,YAXIS,PKT Ø22
ALIGNMENT/TRANS,ZAXIS,PKT Ø22
ALIGNMENT/END
COMMENT/OPER,NO,FULL SCREEN=NO,AUTO-CONTINUE=NO,
Mät spår i konsol

OBS! Börja med tre stödpunkter!
SPÅR =FEAT/CONTACT/ROUND SLOT/DEFAULT,CARTESIAN,IN
THEO/<295.6,-104.3,-147.2>,<-0.0605674,0.5000144,0.8638965>,<0.997564,0.0003141 ,0.069757>,9,11.8
ACTL/<-245.688,-241.238,-30.76>,<0.7142378,0.0169459,0.6996979>,<0.3198843, 0.8812814,-0.3478752>,9.169,13.982
TARG/<295.6,-104.3,-147.2>,<-0.0605674,0.5000144,0.8638965>,<0.997564,0.0003141 ,0.069757>
MEAS ANGLE=160
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
PKT Q =FEAT/POINT,CARTESIAN,YES
THEO/<295.6,-104.3,-147.2>,<-0.0605674,0.5000144,0.8638965>
ACTL/<-245.688,-241.238,-30.76>,<0.7142378,0.0169459,0.6996979>
CONSTR/POINT,CAST,SPÅR
A2 =ALIGNMENT/START,RECALL:A1,LIST=YES
ALIGNMENT/BF2D,ZPLUS,LEAST_SQR,CREATE WEIGHTS=NO,ROTANDTRANS,USE SCALING=NO,0,0,0,26.844
ITERATEANDREPIERCECAD=NO
Deviation Threshold=5,Pause Execution=NO
SHOWALLINPUTS=NO,SHOWALLPARAMS=NO
ALIGNMENT/END
WORKPLANE/YPLUS
A3 =ALIGNMENT/START,RECALL:A2,LIST=YES
ALIGNMENT/BF2D,YPLUS,LEAST_SQR,CREATE WEIGHTS=NO,ROTANDTRANS,USE SCALING=NO,0,0,0,21.172
ITERATEANDREPIERCECAD=NO
Deviation Threshold=5,Pause Execution=NO
SHOWALLINPUTS=NO,SHOWALLPARAMS=NO
ALIGNMENT/END
WORKPLANE/ZPLUS
COMMENT/OPER,NO,FULL SCREEN=NO,AUTO-CONTINUE=NO,
Mät ytterdiameter på höger rörände

OBS! Börja med tre stödpunkter!
HÖ RÖRÄNDE =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
THEO/<253,-142.5,-171.7>,<-0.2686794,-0.9630455,-0.0188342>,18,0
ACTL/<-285.276,-50.326,-175.445>,<-0.4032534,0.9128111,-0.0645188>,18.067,0
TARG/<253,-142.5,-171.7>,<-0.2686794,-0.9630455,-0.0188342>
START ANG=0,END ANG=360
ANGLE VEC=<-0.0699277,0,0.9975521>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
COMMENT/OPER,NO,FULL SCREEN=NO,AUTO-CONTINUE=NO,
Mät ytterdiameter på Ø16

OBS! Börja med tre stödpunkter!
Ø16 =FEAT/CONTACT/CIRCLE/DEFAULT,CARTESIAN,OUT,LEAST_SQR
THEO/<142.3,56.6,-226.6>,<0.4444073,0.8166771,-0.3681585>,16,0
ACTL/<-74.943,-141.655,-220.667>,<0.1179681,-0.9436953,-0.3090674>,16.024,0
TARG/<142.3,56.6,-226.6>,<0.4444073,0.8166771,-0.3681585>
START ANG=0,END ANG=360
ANGLE VEC=<-0.6379514,0,-0.7700766>
DIRECTION=CCW
SHOW FEATURE PARAMETERS=NO
SHOW CONTACT PARAMETERS=NO
WORKPLANE/ZPLUS
A4 =ALIGNMENT/START,RECALL:A3,LIST=YES
ALIGNMENT/BF3D,LEAST_SQR,CREATE WEIGHTS=NO,ROTANDTRANS,USE SCALING=NO,-1.755,3.229,-0.217,-141.985,175.886,-1.101
ITERATEANDREPIERCECAD=NO
Deviation Threshold=5,Pause Execution=NO
SHOWALLINPUTS=NO,SHOWALLPARAMS=NO
ALIGNMENT/END
REF A =FEAT/PLANE,CARTESIAN,TRIANGLE,NO
THEO/<0,0,0>,<0,0,1>
ACTL/<0,0,0>,<0,0,1>
CONSTR/PLANE,ALIGN,ZPLUS
DATDEF/A,FEATURES=REF A,,
REF C =FEAT/PLANE,CARTESIAN,TRIANGLE,NO
THEO/<0,0,0>,<0,1,0>
ACTL/<0,0,0>,<0,1,0>
CONSTR/PLANE,ALIGN,YPLUS
DATDEF/C,FEATURES=REF C,,
DIM DIM3= LOCATION OF CIRCLE Ø22 UNITS=MM ,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=NONE HALF ANGLE=NO
AX MEAS NOMINAL +TOL -TOL DEV OUTTOL
X 0.610 0.000 0.000 0.000 0.610 0.610 ->
Y 3.631 0.000 0.000 0.000 3.631 3.631 ->
Z 0.000 0.000 0.000 0.000 0.000 0.000 ->
END OF DIMENSION DIM3
DIM DIM2= LOCATION OF POINT PKT Q UNITS=MM ,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=NONE HALF ANGLE=NO
AX MEAS NOMINAL +TOL -TOL DEV OUTTOL
X 294.187 295.600 0.000 0.000 -1.413 -1.413 <-
Y -104.300 -104.300 0.000 0.000 0.000 0.000 ->
Z -147.200 -147.200 0.000 0.000 0.000 0.000 ->
END OF DIMENSION DIM2
COMMENT/REPT,
Mått 295.6 (±2)
DIM DIM4= LOCATION OF SLOT SPÅR UNITS=MM ,$
GRAPH=OFF TEXT=OFF MULT=10.00 OUTPUT=BOTH HALF ANGLE=NO
AX MEAS NOMINAL +TOL -TOL DEV OUTTOL
X 294.187 295.600 2.000 -2.000 -1.413 0.000 #-
END OF DIMENSION DIM4
COMMENT/REPT,
Lägeriktighet inom Ø2(M) rel. A/C för Ø22
FCFDIM1 =GEOMETRIC_TOLERANCE/STANDARD=ISO 1101,SHOWEXPANDED=NO,
SIZE/NOMINAL=22,TOLERANCE SPECIFICATION MODE=NOMINAL_WITH_DEVIATIONS,
UPPER TOLERANCE=0.15,LOWER TOLERANCE=-0.15,
SEGMENT_1,POSITION,DIAMETER,2,MMC,A,C,<dat>,
ADD
FEATURES/Ø22,,
COMMENT/REPT,
Lägeriktighet inom Ø4(M) rel. A/C för Ø16
FCFDIM2 =GEOMETRIC_TOLERANCE/STANDARD=ISO 1101,SHOWEXPANDED=NO,
SIZE/NOMINAL=16,TOLERANCE SPECIFICATION MODE=NOMINAL_WITH_DEVIATIONS,
UPPER TOLERANCE=0.1,LOWER TOLERANCE=-0.1,
SEGMENT_1,POSITION,DIAMETER,4,MMC,A,C,<dat>,
ADD
FEATURES/Ø16,,
COMMENT/REPT,
Lägeriktighet inom Ø4(M) rel. A/C för Ø18
FCFDIM3 =GEOMETRIC_TOLERANCE/STANDARD=ISO 1101,SHOWEXPANDED=NO,
SIZE/NOMINAL=18,TOLERANCE SPECIFICATION MODE=NOMINAL_WITH_DEVIATIONS,
UPPER TOLERANCE=0.1,LOWER TOLERANCE=-0.1,
SEGMENT_1,POSITION,DIAMETER,4,MMC,A,C,<dat>,
ADD
FEATURES/HÖ RÖRÄNDE,,


​​​​​Ping neil.challinor
  • Maybe it has to do with the constructed planes and fitting algorithms? The second picture is cut off and I can't read Swedish, but did you try Current Alignment vs Datum Reference Frame?
  • Yep, datum ref yields no dimensions that I can relate to, current alignment shows those numbers above. I have tried adding datums/removing datums but I cannot get the "correct" nominals at all... Contructed planes is a no-go in GeoTol perhaps? Then I am doomed to use versions no later than 2019...
  • The two first ones are using constraints to align to a slot in two different 2D-planes, the third is a final alignment, I hope I got them right. Program works as expected in 2019 SP11.
  • I am leaning towards that the problem is that I'm using planes without surface data (primary and secondary datums) as they are constructed from the alignment. According to the help file, the MEAS data is used for planes without surface data. But why is it changing the nominals. It should not do that - ever.
  • I am leaning towards that the problem is that I'm using planes without surface data (primary and secondary datums) as they are constructed from the alignment. According to the help file, the MEAS data is used for planes without surface data. But why is it changing the nominals. It should not do that - ever.


    Just humor us: What if you added in an alignment with your constructed planes? Does it change the nominals on your features?
  • Nope. Something is happening inside the GeoTol evaluation that causes some kind of shift on the nominals.
  • Small difference on X after aligning using the planes:

  • The nominal values displayed in the report are the closest nominal value to the measured point. The DRF defines a cylindrical tolerance zone that is not aligned to either the X, Y or Z axis. The circle being reported is allowed to move axially within that tolerance zone and so the X, Y & Z nominals returned by the GD&T library can change depending on that axial shift.

    The same phenomenon can be seen If you create a cylinder in the ZPLUS workplane and report diametrical position in X & Y. The X & Y nominal values will remain fixed whereas the Z nominal will vary depending on whether the start point or end point of the cylinder yields the worst positional error. For a planar position, the nominal in the planar direction will remain fixed whilst nominals for the other two axes are free to change.

    This only happens on the report, the nominals shown on the nominals tab of the geometric tolerance command will not change and will always reflect the THEO value of the feature.

    Although this approach is technically more accurate, correct as per the standards and does not affect the measured value being reported (the measured value is correct and you should be able to calculate it from the deviation values), it appears to be causing confusion amongst some users. Based on feedback we have received, we are currently working on a change to the design. The change would mean that the nominals shown in the dialog always reflect the start point of the feature (they currently represent the average) and the nominals in the report would always reflect either the start or end point - whichever was the worst (same as XactMeasure).
  • Thanks neil.challinor !
    Your cylinder example brought me back on track. None of the "funky" TP's are perp nor parallel to the axises, so that makes sense.

    In short, the nominals displayed are the closest nominals to the measured point within the tolerance zone?